title: [Temporal variation of genotypes and serotypes of enterohemorrhagic E Coli isolated from Chilean children with intestinal infections or hemolytic uremic syndrome].
abstract: BACKGROUND
  Infections by enterohemorrhagic E. Coli may be asymptomatic, may cause diarrhea, sometimes bloody or a hemolytic uremic syndrome in 2 to 7% of children. These diseases appear sporadically or as outbreaks. Host and agent factors influence the appearance of hemolytic uremic syndrome.
  
  
  OBJECTIVE
  To study the distributions and prevalence of virulence genes and enterohemorrhagic E. Coli serogroups isolated from Chilean children.
  
  
  METHODS
  Thirty six strains isolated from children with hemolytic uremic syndrome (8 obtained in 1988-1989, 15 obtained in 1990-1993 and 13 obtained in 1995-1996), 33 strains from asymptomatic children, obtained in similar periods and 30 strains from children with bloody diarrhea, obtained in 1995-1996 were studied. Virulence factors were investigated with a colony hybridization technique using probes that identify virulence genes. Serotypes were identified with commercial antisera.
  
  
  RESULTS
  Both SLTI and SLTII genes predominated in strains obtained from children with hemolytic uremic syndrome in 1988-1989 and 1995-1996 and SLTI gene predominated in strains obtained in 1990-1993. Similar temporal variations in virulence genes of strains obtained from asymptomatic children were observed. SLTI/SLTII pattern predominated in strains obtained from children with bloody diarrhea and the frequency of O157 serogroup was lower, compared to strains obtained from children with hemolytic uremic syndrome.
  
  
  CONCLUSIONS
  There was a temporal variation in toxigenic genotypes of enterohemorrhagic E. Coli strains, but no association between these genotypes and the risk for hemolytic uremic syndrome was observed.
authors.affiliation: Unidad de Microbiología, Facultad de Medicina, Universidad de Chile, Santiago de Chile.
authors.forename: V
authors.initials: V
authors.lastname: Prado
authors.forename: J
authors.initials: J
authors.lastname: Martínez
authors.forename: C
authors.initials: C
authors.lastname: Arellano
authors.forename: M M
authors.initials: MM
authors.lastname: Levine
mesh_terms: D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D002677:Chile; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D005838:Genotype; D006463:Hemolytic-Uremic Syndrome / Q000382:microbiology*; D006801:Humans; D007410:Intestinal Diseases / Q000382:microbiology; D012703:Serotyping
vernacular_title: Variación temporal de genotipos y serogrupos de E coli enterohemorrágicos aislados en niños chilenos con infecciones intestinales o sindrome hemolítico-urémico.